Multi-Layered Bags With Discrete Non-Continuous Lamination

ABSTRACT

Multi-layer bags may be formed to include first and second sidewalls joined along a first side edge, an opposite second side edge, and a closed bottom edge. The first and second layers may be non-continuously laminated together in discrete sections to include bonded regions in which the layers are bonded and unbonded regions in which the layers are not bonded. Such a bag may be described as a “bag-in-a-bag” type configuration in which the inner bag is non-continuously bonded to the outer bag. The inventors have surprisingly found that such configurations of non-continuous bonding provides increased and unexpected strength properties to the multi-layer films and bags.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation in part of U.S. patentapplication Ser. No. 12/947,025 filed Nov. 16, 2010 and entitledDISCONTINUOUSLY LAMINATED FILM, which claims the benefit of U.S.Provisional Application No. 61/261,673, filed Nov. 16, 2009. Each of theabove-referenced applications is hereby incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates generally to thermoplastic films.Specifically, the invention relates to stretched thermoplastic filmswith visually distinct regions created by stretching the films.

2. Background and Relevant Art

Thermoplastic films are a common component in various commercial andconsumer products. For example, grocery bags, trash bags, sacks, andpackaging materials are products that are commonly made fromthermoplastic films. Additionally, feminine hygiene products, babydiapers, adult incontinence products, and many other products includethermoplastic films to one extent or another.

Thermoplastic films have a variety of different strength parameters thatmanufacturers of products incorporating a thermoplastic film componentmay attempt to manipulate to ensure that the film is suitable for useits intended use. For example, manufacturers may attempt to increase orotherwise control the tensile strength, tear resistance, and impactresistance of a thermoplastic film. One way manufacturers may attempt tocontrol or change the material properties of a thermoplastic film is bystretching the film. Common directions of stretching include “machinedirection” and “transverse direction” stretching. As used herein, theterm “machine direction” or “MD” refers to the direction along thelength of the film, or in other words, the direction of the film as thefilm is formed during extrusion and/or coating. As used herein, the term“transverse direction” or “TD” refers to the direction across the filmor perpendicular to the machine direction.

Common ways of stretching film in the machine direction include machinedirection orientation (“MDO”) and incremental stretching. MDO involvesstretching the film between two pairs of smooth rollers. Commonly MDOinvolves running a film through the nips of sequential pairs of smoothrollers. The first pair of rollers rotates at a speed less than that ofthe second pair of rollers. The difference in speed of rotation of thepairs of rollers can cause the film between the pairs of rollers tostretch. The ratio of the roller speeds will roughly determine theamount that the film is stretched. For example, if the first pair ofrollers is rotating at 100 feet per minute (“fpm”) and the second pairof rollers is rotating at 500 fpm, the rollers will stretch the film toroughly five times its original length. MDO stretches the filmcontinuously in the machine direction and is often used to create anoriented film.

Incremental stretching of thermoplastic film, on the other hand,typically involves running the film between grooved or toothed rollers.The grooves or teeth on the rollers intermesh and stretch the film asthe film passes between the rollers. Incremental stretching can stretcha film in many small increments that are spaced across the film. Thedepth at which the intermeshing teeth engage can control the degree ofstretching. Often, incremental stretching of films is referred to asring rolling.

In addition to allowing for the modification or tailoring of thestrength of a film, stretching of a film can also reduce the thicknessof the film. Stretched films of reduced thickness can allowmanufacturers to use less thermoplastic material to form a product of agiven surface area or size. Unfortunately, stretching thermoplasticusing conventional methods can weaken the film.

One common use of thermoplastic films is as bags for liners in trash orrefuse receptacles. Another common use of thermoplastic films is asflexible plastic bags for storing food items.

BRIEF SUMMARY OF THE INVENTION

Implementations of the present invention solve one or more problems inthe art with apparatus and methods for creating multi-layered bags withdiscrete non-continuous lamentation. In particular, one or moreimplementations provide for forming bonds between adjacent layers of amulti-layer film or bag that are relatively light such that forcesacting on the multi-layer film are first absorbed by breaking the bondsrather than, or prior to, tearing or otherwise causing the failure ofthe layers of the multi-layer film or bag. Such implementations canprovide an overall thinner film employing a reduced amount of rawmaterial that nonetheless has maintained or increased strengthparameters. Alternatively, such implementations can use a given amountof raw material and provide a film with increased strength parameters.Furthermore, discrete areas of the multi-layered bags can includedifferent bonding to provide different strength and/or aestheticcharacteristics to the multi-layered bags.

For example, one implementation of a thermoplastic bag with a bag-in-bagconfiguration includes a first thermoplastic bag and a secondthermoplastic bag positioned within the first thermoplastic bag. Each ofthe first and second thermoplastic bags can have at least a bottomsection, a middle section, and an upper section. The first thermoplasticbag also includes first and second opposing sidewalls joined togetheralong three edges. The second thermoplastic bag includes third andfourth opposing sidewalls joined together along three edges. A pluralityof non-continuous bonded regions secure at least one of the respectivebottom sections, middle sections, or upper sections of the firstthermoplastic bag and the second thermoplastic bag together.

Another implementation of the present invention includes a multi-layeredbag comprising a first sidewall comprising a first layer of athermoplastic material and an adjacent second layer of thermoplasticmaterial. The multi-layered bag also includes a second sidewallcomprising a first layer of a thermoplastic material and an adjacentsecond layer of thermoplastic material. The second sidewall is joined tothe first sidewall along a first side edge, an opposing second sideedge, and a bottom edge. At least a portion of the respective top edgesof the first and second sidewalls define an opening of the multi-layeredbag. A first plurality of non-continuous bonds secures at least onesection of the first and second layers of the first sidewall together.Additionally, a second plurality of non-continuous bonds secures atleast another section of the first and second layers of the firstsidewall together. The second plurality of non-continuous bonds differsfrom the first plurality of non-continuous bonds.

In addition to the forgoing, a method for forming a discretelylaminated, multi-layered thermoplastic bag may involve providing firstand second thermoplastic films. The method can also involvenon-continuously laminating a portion of the first thermoplastic film tothe second thermoplastic film by a process selected from the groupconsisting of adhesive bonding, ultrasonic bonding, embossing, ringrolling, SELFing, and combinations thereof. Additionally, the method caninvolve joining at least two edges of the first thermoplastic film andthe second thermoplastic film together to form a bag configuration.

Additional features and advantages of exemplary embodiments of thepresent invention will be set forth in the description which follows,and in part will be obvious from the description, or may be learned bythe practice of such exemplary embodiments. The features and advantagesof such embodiments may be realized and obtained by means of theinstruments and combinations particularly pointed out in the appendedclaims. These and other features will become more fully apparent fromthe following description and appended claims, or may be learned by thepractice of such exemplary embodiments as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the invention can be obtained, a moreparticular description of the invention briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It should be noted that thefigures are not drawn to scale, and that elements of similar structureor function are generally represented by like reference numerals forillustrative purposes throughout the figures. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered to be limiting of its scope, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1A illustrates a schematic diagram of a multi-layered film beinglightly laminated by MD intermeshing rollers in accordance with one ormore implementations of the present invention;

FIG. 1B illustrates an enlarged view of two initially separatethermoplastic films passing together through the intermeshing rollers ofFIG. 1A taken along the circle 1B of FIG. 1 to form a multi-layeredlightly-laminated;

FIG. 1C illustrates an enlarged view of three initially separatethermoplastic films passing together through the intermeshing rollers ofFIG. 1A to form a multi-layered lightly-laminated;

FIG. 2 illustrates a view of a multi-layered lightly-laminatedthermoplastic film created by the intermeshing rollers of FIG. 1A;

FIG. 3 illustrates a schematic diagram of a multi-layered thermoplasticfilm being lightly laminated by TD intermeshing rollers in accordancewith one or more implementations of the present invention;

FIG. 4 illustrates a view of a multi-layered lightly-laminatedthermoplastic film created by the intermeshing rollers of FIG. 3;

FIG. 5 illustrates a view of a multi-layered lightly-laminatedthermoplastic film created by the intermeshing rollers of both FIG. 1Aand FIG. 3;

FIG. 6 illustrates a view of a multi-layered lightly-laminatedthermoplastic film created by diagonal direction intermeshing rollers inaccordance with one or more implementations of the present invention;

FIG. 7 illustrates a schematic diagram of a set of intermeshing rollersused to form a structural elastic like film (SELF) by impartingstrainable networks into the film while lightly laminating adjacentlayers of a film in accordance with one or more implementations of thepresent invention;

FIG. 8 illustrates a view of a multi-layered lightly-laminatedthermoplastic film created by the intermeshing rollers of FIG. 7;

FIG. 9 illustrates a view of another multi-layered lightly-laminatedthermoplastic film including strainable networks in accordance with oneor more implementations of the present invention;

FIG. 10A illustrates a view of yet another multi-layeredlightly-laminated thermoplastic film including strainable networks inaccordance with one or more implementations of the present invention;

FIG. 10B illustrates a cut away perspective view across and through theblock pattern of FIG. 10A;

FIG. 11A illustrates a schematic diagram of another implementation ofintermeshing rollers for use in accordance with one or moreimplementations of the present invention;

FIG. 11B illustrates a close up of the protrusions and intermeshingrecessions of the rollers of FIG. 11A;

FIG. 11C illustrates a view of a multi-layered lightly-laminatedthermoplastic film created by the intermeshing rollers of FIG. 11A;

FIG. 12A illustrates a multi-layered bag with discrete non-continuouslamination in accordance with one or more implementations of the presentinvention;

FIG. 12B illustrates a cross-sectional view of the bag of FIG. 12A takenalong the line 12B-12B of FIG. 12A;

FIG. 13 illustrates another multi-layered bag with discretenon-continuous lamination in accordance with one or more implementationsof the present invention;

FIG. 14 illustrates yet another multi-layered bag with discretenon-continuous lamination in accordance with one or more implementationsof the present invention;

FIG. 15 illustrates a another multi-layered bag with discretenon-continuous lamination incorporating sections of different patternsof lightly bonded regions in accordance with one or more implementationsof the present invention;

FIG. 16 illustrates another multi-layered bag with discretenon-continuous lamination incorporating sections of different patternsof lightly bonded regions in accordance with one or more implementationsof the present invention;

FIG. 17 illustrates another multi-layered bag with discretenon-continuous lamination in accordance with one or more implementationsof the present invention;

FIG. 18 illustrates another multi-layered bag with discretenon-continuous lamination incorporating a top section having lightlybonded regions in accordance with one or more implementations of thepresent invention;

FIG. 19 illustrates another multi-layered bag with discretenon-continuous lamination with another bond pattern in accordance withone or more implementations of the present invention;

FIG. 20 illustrates another multi-layered bag with discretenon-continuous lamination with yet another bond pattern in accordancewith one or more implementations of the present invention;

FIG. 21 illustrates another multi-layered bag with discretenon-continuous lamination incorporating a top section and a bottomsection having lightly bonded regions in accordance with one or moreimplementations of the present invention;

FIG. 22 illustrates another multi-layered bag with discretenon-continuous lamination incorporating a top section having lightlybonded regions in accordance with one or more implementations of thepresent invention;

FIG. 23 illustrates another multi-layered bag with discretenon-continuous lamination incorporating a top section and a bottomsection having lightly bonded regions, each of a different pattern, inaccordance with one or more implementations of the present invention;

FIG. 24 illustrates another multi-layered bag with discretenon-continuous lamination incorporating a top section having lightlybonded regions in accordance with one or more implementations of thepresent invention;

FIG. 25 illustrates still another multi-layered bag with discretenon-continuous lamination incorporating a top section and a bottomsection having lightly bonded regions in accordance with one or moreimplementations of the present invention;

FIG. 26 illustrates a schematic diagram of a bag manufacturing processin accordance with one or more implementations of the present invention;

FIG. 27 illustrates a schematic diagram of another bag manufacturingprocess in accordance with one or more implementations of the presentinvention; and

FIG. 28 illustrates a schematic diagram of another bag manufacturingprocess in accordance with one or more implementations of the presentinvention.

DETAILED DESCRIPTION

One or more implementations of the present invention include apparatusand methods for creating multi-layered bags with discrete non-continuouslamentation. In particular, one or more implementations provide forforming bonds between adjacent layers of a multi-layer film or bag thatare relatively light such that forces acting on the multi-layer film arefirst absorbed by breaking the bonds rather than, or prior to, tearingor otherwise causing the failure of the layers of the multi-layer filmor bag. Such implementations can provide an overall thinner filmemploying a reduced amount of raw material that nonetheless hasmaintained or increased strength parameters. Alternatively, suchimplementations can use a given amount of raw material and provide afilm with increased strength parameters. Furthermore, discrete areas ofthe multi-layered bags can include different bonding to providedifferent strength and/or aesthetic characteristics to the multi-layeredbags.

In particular, the non-continuous bonds or bond regions of adjacentlayers of multi-layer films or bags in accordance with one or moreimplementations can act to first absorb forces via breaking of the bondsprior to allowing that same force to cause failure of the individuallayers of the multi-layer film or bag. Such action can provide increasedstrength to the multi-layer film or bag. In one or more implementations,the non-continuous bonds or bond regions include a bond strength that isadvantageously less than a weakest tear resistance of each of theindividual films so as to cause the bonds to fail prior to failing ofthe film layers. Indeed, one or more implementations include bonds thatthe release just prior to any localized tearing of the layers of themulti-layer bag.

Thus, in one or more implementations, the non-continuous bonds or bondregions of a multi-layer film or bag can fail before either of theindividual layers undergo molecular-level deformation. For example, anapplied strain can pull the non-continuous bonds or bond regions apartprior to any molecular-level deformation (stretching, tearing,puncturing, etc.) of the individual film layers. In other words, thelight bonds or bond regions can provide less resistive force to anapplied strain than molecular-level deformation of any of the layers ofthe multi-layer film or bag. The inventors have surprisingly found thatsuch a configuration of light bonding can provide increased strengthproperties to the multi-layer film or bag as compared to a film or bagwith a monolayer equal thickness or a multi-layer film or bag in whichthe plurality of layers are tightly bonded together (e.g., coextruded).

One or more implementations of the present invention provide fortailoring the bonds or bond regions between layers of a multi-layer bagin different regions of the bag. For example, one or moreimplementations include modifying or tailoring one or more of bondstrength, bond density, bond pattern, bond type and/or bond size ofdifferent sections of a multi-layer film or bag to deliver a bag withzones or sections with tailored strength and/or aestheticcharacteristics.

Relatively weak bonding of the two or more layers of the multi-layerfilm or bag can be accomplished through one or more suitable techniques.For example, bonding may be achieved by pressure (for example MD ringrolling, TD ring rolling, stainable network lamination, or embossing),or with a combination of heat and pressure. Alternately, the film layerscan be lightly laminated by ultrasonic bonding. Alternately, the filmscan be laminated by adhesives. Treatment with a Corona discharge canenhance any of the above methods. Prior to lamination, the separatelayers can be flat film or can be subject to separate processes, such asstretching, slitting, coating and printing, and corona treatment.

As used herein, the terms “lamination,” “laminate,” and “laminatedfilm,” refer to the process and resulting product made by bondingtogether two or more layers of film or other material. The term“bonding”, when used in reference to bonding of multiple layers of amulti-layer film, may be used interchangeably with “lamination” of thelayers. According to methods of the present invention, adjacent layersof a multi-layer film are laminated or bonded to one another. Thebonding purposely results in a relatively weak bond between the layersthat has a bond strength that is less than the strength of the weakestlayer of the film. This allows the lamination bonds to fail before thefilm layer, and thus the film, fails.

The term laminate is also inclusive of coextruded multilayer filmscomprising one or more tie layers. As a verb, “laminate” means to affixor adhere (by means of, for example, adhesive bonding, pressure bonding,ultrasonic bonding, corona lamination, and the like) two or moreseparately made film articles to one another so as to form a multi-layerstructure. As a noun, “laminate” means a product produced by theaffixing or adhering just described.

The individual layers of the multi-layer film may each themselvescomprise a plurality of laminated layers. Such layers may besignificantly more tightly bonded together than the bonding provided bythe purposely weak non-continuous bonding in the finished multi-layerfilm. Both tight and relatively weak lamination can be accomplished byjoining layers by mechanical pressure, joining layers with adhesives,joining with heat and pressure, spread coating, extrusion coating, andcombinations thereof. Adjacent sub-layers of an individual layer may becoextruded. Coextrusion results in tight bonding so that the bondstrength is greater than the tear resistance of the resulting laminate(i.e., rather than allowing adjacent layers to be peeled apart throughbreakage of the lamination bonds, the film will tear).

In one or more implementations, the light lamination or bonding betweenlayers of a multi-layer film may be non-continuous (i.e., discontinuousor partial discontinuous). As used herein the terms “discontinuousbonding” or “discontinuous lamination” refers to lamination of two ormore layers where the lamination is not continuous in the machinedirection and not continuous in the transverse direction. Moreparticularly, discontinuous lamination refers to lamination of two ormore layers with repeating bonded patterns broken up by repeatingun-bonded areas in both the machine direction and the transversedirection of the film.

As used herein the terms “partially discontinuous bonding” or “partiallydiscontinuous lamination” refers to lamination of two or more layerswhere the lamination is substantially continuous in the machinedirection or in the transverse direction, but not continuous in theother of the machine direction or the transverse direction. Alternately,partially discontinuous lamination refers to lamination of two or morelayers where the lamination is substantially continuous in the width ofthe article but not continuous in the height of the article, orsubstantially continuous in the height of the article but not continuousin the width of the article. More particularly, partially discontinuouslamination refers to lamination of two or more layers with repeatingbonded patterns broken up by repeating unbounded areas in either themachine direction or the transverse direction.

As used herein, the term “flexible” refers to materials that are capableof being flexed or bent, especially repeatedly, such that they arepliant and yieldable in response to externally applied forces.Accordingly, “flexible” is substantially opposite in meaning to theterms inflexible, rigid, or unyielding. Materials and structures thatare flexible, therefore, may be altered in shape and structure toaccommodate external forces and to conform to the shape of objectsbrought into contact with them without losing their integrity. Inaccordance with further prior art materials, web materials are providedwhich exhibit an “elastic-like” behavior in the direction of appliedstrain without the use of added traditional elastic. As used herein, theterm “elastic-like” describes the behavior of web materials which whensubjected to an applied strain, the web materials extend in thedirection of applied strain, and when the applied strain is released theweb materials return, to a degree, to their pre-strained condition.

As used herein, the term “starting gauge” or “initial gauge” refers tothe average distance between the major surfaces of a film before it isincrementally stretched so as to discontinuously bond adjacent layerstogether. Of course, it is also possible to stretch one or more of theindividual layers before they are discontinuously bonded together.

Methods of providing relatively weak bonding of adjacent layers (i.e.,so that the bond strength is less than a weakest tear resistance of theindividual layers) can include many techniques, such as adhesivebonding, pressure bonding, ultrasonic bonding, and corona lamination. MDring rolling, TD ring rolling, or other ring rolling processes (e.g., DDring rolling or ring rolling that results in a thermoplastic film withstrainable networks), and combinations thereof may be used tonon-continuously bond adjacent layers of the multilayer film, as will bedescribed in further detail below.

Film Materials

As an initial matter, one or more layers of the films can comprise anyflexible or pliable material comprising a thermoplastic material andthat can be formed or drawn into a web or film. As described above, thefilm includes a plurality of layers of thermoplastic films. Eachindividual film layer may itself include a single layer or multiplelayers. Adjuncts may also be included, as desired (e.g., pigments, slipagents, anti-block agents, tackifiers, or combinations thereof). Thethermoplastic material of the films of one or more implementations caninclude, but are not limited to, thermoplastic polyolefins, includingpolyethylene, polypropylene, and copolymers thereof. Besides ethyleneand propylene, exemplary copolymer olefins include, but are not limitedto, ethylene vinylacetate (EVA), ethylene methyl acrylate (EMA) andethylene acrylic acid (EAA), or blends of such olefins. Various othersuitable olefins and polyolefins will be apparent to one of skill in theart.

Other examples of polymers suitable for use as films in accordance withthe present invention include elastomeric polymers. Suitable elastomericpolymers may also be biodegradable or environmentally degradable.Suitable elastomeric polymers for the film includepoly(ethylene-butene), poly(ethylene-hexene), poly(ethylene-octene),poly(ethylene-propylene), poly(styrene-butadiene-styrene),poly(styrene-isoprene-styrene), poly(styrene-ethylene-butylene-styrene),poly(ester-ether), poly(ether-amide), poly(ethylene-vinylacetate),poly(ethylene-methylacrylate), poly(ethylene-acrylic acid),poly(ethylene butylacrylate), polyurethane,poly(ethylene-propylene-diene), ethylene-propylene rubber, andcombinations thereof.

In at least one implementation of the present invention, the film caninclude linear low density polyethylene. The term “linear low densitypolyethylene” (LLDPE) as used herein is defined to mean a copolymer ofethylene and a minor amount of an alkene containing 4 to 10 carbonatoms, having a density of from about 0.910 to about 0.926 g/cm³, and amelt index (MI) of from about 0.5 to about 10. For example, one or moreimplementations of the present invention can use an octene co-monomer,solution phase LLDPE (MI=1.1; ρ=0.920). Additionally, otherimplementations of the present invention can use a gas phase LLDPE,which is a hexene gas phase LLDPE formulated with slip/AB (MI=1.0;ρ=0.920). One will appreciate that the present invention is not limitedto LLDPE, and can include “high density polyethylene” (HDPE), “lowdensity polyethylene” (LDPE), and “very low density polyethylene”(VLDPE). Indeed films made from any of the previously mentionedthermoplastic materials or combinations thereof can be suitable for usewith the present invention.

One will appreciate in light of the disclosure herein that manufacturersmay form the individual films or webs to be non-continuously bondedtogether so as to provide improved strength characteristics using a widevariety of techniques. For example, a manufacturer can form a precursormix of the thermoplastic material including any optional additives. Themanufacturer can then form the film(s) from the precursor mix usingconventional flat extrusion, cast extrusion, or coextrusion to producemonolayer, bilayer, or multilayered films. In any case, the resultingfilm will be discontinuously bonded to another film at a later stage toprovide the benefits associated with the present invention.

Alternative to conventional flat extrusion or cast extrusion processes,a manufacturer can form the films using other suitable processes, suchas, a blown film process to produce monolayer, bilayer, or multilayeredfilms, which are subsequently discontinuously bonded with another filmlayer at a later stage. If desired for a given end use, the manufacturercan orient the films by trapped bubble, tenterframe, or other suitableprocesses. Additionally, the manufacturer can optionally anneal thefilms.

The extruder used can be of a conventional design using a die, whichwill provide the desired gauge. Some useful extruders are described inU.S. Pat. Nos. 4,814,135; 4,857,600; 5,076,988; 5,153,382; each of whichare incorporated herein by reference in their entirety. Examples ofvarious extruders, which can be used in producing the films to be usedwith the present invention, can be a single screw type modified with ablown film die, an air ring, and continuous take off equipment.

In one or more implementations, a manufacturer can use multipleextruders to supply different melt streams, which a feed block can orderinto different channels of a multi-channel die. The multiple extruderscan allow a manufacturer to form a multi-layered film with layers havingdifferent compositions. Such multi-layer film may later benon-continuously laminated with another layer of film to provide thebenefits of the present invention.

In a blown film process, the die can be an upright cylinder with acircular opening. Rollers can pull molten plastic upward away from thedie. An air-ring can cool the film as the film travels upwards. An airoutlet can force compressed air into the center of the extruded circularprofile, creating a bubble. The air can expand the extruded circularcross section by a multiple of the die diameter. This ratio is calledthe “blow-up ratio.” When using a blown film process, the manufacturercan collapse the film to double the plies of the film. Alternatively,the manufacturer can cut and fold the film, or cut and leave the filmunfolded.

The films of one or more implementations of the present invention canhave a starting gauge between about 0.1 mils to about 20 mils, suitablyfrom about 0.2 mils to about 4 mils, suitably in the range of about 0.3mils to about 2 mils, suitably from about 0.6 mils to about 1.25 mils,suitably from about 0.9 mils to about 1.1 mils, suitably from about 0.3mils to about 0.7 mils, and suitably from about 0.4 mils and about 0.6mils. Additionally, the starting gauge of films of one or moreimplementations of the present invention may not be uniform. Thus, thestarting gauge of films of one or more implementations of the presentinvention may vary along the length and/or width of the film.

As previously mentioned, according to one implementation of theinvention, the separate layers of the multi-layer film arenon-continuously, lightly bonded to one another. FIGS. 1A-1C illustrateexemplary processes of partially discontinuously bonding adjacent layersof a multi-layer thermoplastic film in accordance with an implementationof the present invention. In particular, FIGS. 1A-1C illustrate an MDring rolling process that partially discontinuously laminates theindividual adjacent layers of thermoplastic multi-layered film 10 bypassing the multi-layered film 10 through a pair of MD intermeshingrollers 12, 14. As a result of MD ring rolling, the multi-layered film10 is also intermittently stretched in the machine direction MD.

As shown by the FIGS. 1A-1C, the first roller 12 and the second roller14 can each have a generally cylindrical shape. The rollers 12, 14 maybe made of cast and/or machined metal, such as, steel, aluminum, or anyother suitable material. The rollers 12, 14 can rotate in oppositedirections about parallel axes of rotation. For example, FIG. 1Aillustrates that the first roller 12 can rotate about a first axis 16 ofrotation in a counterclockwise direction 18. FIG. 1A also illustratesthat the second roller 14 can rotate about a second axis 20 of rotationin a clockwise direction 22. The axes of rotation 16, 20 can be parallelto the transverse direction TD and perpendicular to the machinedirection MD.

The intermeshing rollers 12, 14 can closely resemble fine pitch spurgears. In particular, the rollers 12, 14 can include a plurality ofprotruding ridges 24, 26. The ridges 24, 26 can extend along the rollers12, 14 in a direction generally parallel to axes of rotation 16, 20.Furthermore, the ridges 24, 26 can extend generally radially outwardfrom the axes of rotation 16, 20. The tips of ridges 24, 26 can have avariety of different shapes and configurations. For example, the tips ofthe ridges 24, 26 can have a rounded shape as shown in FIGS. 1B-1C. Inalternative implementations, the tips of the ridges 24, 26 can havesharp angled corners. FIGS. 1A-1C also illustrate that grooves 28, 30can separate adjacent ridges 24, 26.

The ridges 24 on the first roller 12 can be offset or staggered withrespect to the ridges 26 on the second roller 14. Thus, the grooves 28of the first roller 12 can receive the ridges 26 of the second roller14, as the rollers 12, 14 intermesh. Similarly, the grooves 30 of thesecond roller 14 can receive the ridges 24 of the first roller 12.

One will appreciate in light of the disclosure herein that theconfiguration of the ridges 24, 26 and grooves 28, 30 can preventcontact between ridges 24, 26 during intermeshing so that no rotationaltorque is transmitted during operation. Additionally, the configurationof the ridges 24, 26 and grooves 28, 30 can affect the amount ofstretching and the bond strength resulting from partially discontinuouslamination as the film passes through intermeshing rollers 12, 14.

Referring specifically to FIGS. 1B-1C, various features of the ridges24, 26 and grooves 28, 30 are shown in greater detail. The pitch anddepth of engagement of the ridges 24, 26 can determine, at least inpart, the amount of incremental stretching and partially discontinuouslamination caused by the intermeshing rollers 12, 14. As shown by FIGS.1B-1C, the pitch 32 is the distance between the tips of two adjacentridges on the same roller. The “depth of engagement” (“DOE”) 34 is theamount of overlap between ridges 24, 26 of the different rollers 12, 14during intermeshing.

The ratio of DOE 34 to pitch 32 can determine, at least in part, thebond strength provided by the partially discontinuous bonding. Accordingto one embodiment, the ratio of DOE to pitch provided by any ringrolling operation is less than about 1.1:1, suitably less than about1.0:1, suitably between about 0.5:1 and about 1.0:1, or suitably betweenabout 0.8:1 and about 0.9:1.

As shown by FIG. 1A, the direction of travel of the multi-layered film10 through the intermeshing rollers 12, 14 is parallel to the machinedirection and perpendicular to the transverse direction. As thethermoplastic multi-layered film 10 passes between the intermeshingrollers 12, 14, the ridges 24, 26 can incrementally stretch themulti-layered film 10 in the machine direction. In one or moreimplementations, stretching the multi-layered film 10 in the machinedirection can reduce the gauge of the film and increase the length ofthe multi-layered film 10. In other implementations, the multi-layeredfilm 10 may rebound after stretching such that the gauge of themulti-layered film 10 is not decreased. Furthermore, in one or moreimplementations, stretching the film 10 in the machine direction canreduce the width of the multi-layered film 10. For example, as themulti-layered film 10 is lengthened in the machine direction, the film'slength can be reduced in the transverse direction.

In particular, as the multi-layered film 10 proceeds between theintermeshing rollers 12, 14, the ridges 24 of the first roller 12 canpush the multi-layered film 10 into the grooves 30 of the second roller14 and vice versa. The pulling of the multi-layered film 10 by theridges 24, 26 can stretch the multi-layered film 10. The rollers 12, 14may not stretch the multi-layered film 10 evenly along its length.Specifically, the rollers 12, 14 can stretch the portions of the film 10between the ridges 24, 26 more than the portions of the multi-layeredfilm 10 that contact the ridges 24, 26. Thus, the rollers 12, 14 canimpart or form a generally striped pattern 36 into the multi-layeredfilm 10. As used herein, the terms “impart” and “form” refer to thecreation of a desired structure or geometry in a film upon stretchingthe film that will at least partially retain the desired structure orgeometry when the film is no longer subject to any strains or externallyapplied forces.

FIGS. 1A-1C illustrate that the film 10 a (i.e., the film that is yet topass through the intermeshing rollers 12, 14) can have a substantiallyflat top surface 38 and substantially flat bottom surface 40. As seen inFIG. 1B, the multi-layer film 10 a may comprise two layers 10 c and 10 dthat are initially separate from one another. The film 10 a can have aninitial thickness or starting gauge 42 (i.e., the sum of 42 a and 42 b)extending between its major surfaces (i.e., the top surface 38 and thebottom surface 40). In at least one implementation, the starting gauge42, as well as the gauge 42 a, 42 b of individual layers 10 c and 10 dcan be substantially uniform along the length of the multi-layer film 10a. Because the inner surfaces of each layer 10 c and 10 d are somewhattacky, the layers become lightly bonded together as they are pulledthrough and stretched by intermeshing rollers 12, 14. Those areas thatare stretched become lightly bonded together.

In one or more implementations, the pre-laminated film 10 a need nothave an entirely flat top surface 38, but may be rough or uneven.Similarly, bottom surface 40 or the inner oriented surfaces of layers 10c and 10 d of the film 10 a can also be rough or uneven. Further, thestarting gauge 42, 42 a, and 42 b need not be consistent or uniformthroughout the entirety of pre-stretched film 10 a. Thus, the startinggauge 42, 42 a, and 42 b can vary due to product design, manufacturingdefects, tolerances, or other processing issues. According to oneembodiment, the individual layers 10 c and 10 d may be pre-stretched(e.g., through MD ring rolling, TD ring rolling, etc.) before beingpositioned adjacent to the other layer (10 d or 10 c, respectively).Such pre-stretching of individual layers can result in a striped surfaceexhibiting an uneven top and bottom surface similar to that seen in FIG.1A.

FIG. 1B illustrates that films 10 a, can include two initially separatefilm layers 10 c-10 d. FIG. 1C illustrates an alternative implementationwhere film 10 a′ (and thus the incrementally stretched film 10 i) caninclude three initially separate film layers: a middle film layer 10 g,and two outer film layers 10 f, 10 h. In other embodiments, more than 3layers may be provided (four, five, six, or more partiallydiscontinuously or discontinuously laminated layers).

As seen in FIG. 1A, upon stretching and partially discontinuouslamination of the adjacent layers, the multi-layered lightly-laminatedfilm 10 b of FIG. 1A, 10 e of FIG. 1B, or film 10 i of FIG. 1C caninclude a striped pattern 36. The striped pattern 36 can includealternating series of un-bonded and un-stretched regions 44 adjacent tobonded and stretched regions 46. FIGS. 1B and 1C illustrate that theintermeshing rollers 12, 14 can incrementally stretch and partiallydiscontinuously bond films 10 a, 10 a′ to create multi-layeredlightly-laminated multi-layer films 10 b, 10 e, 10 i including bondedregions 46 and un-bonded regions 44.

For example, FIG. 1B illustrates that the film layers 11 a, 11 b of themulti-layered lightly-laminated film 10 e can be laminated together atthe stretched regions 46, while the un-stretched regions 44 may not belaminated together. Similarly, FIG. 1C illustrates that the film layers11 c, 11 d, 11 e of the multi-layered lightly-laminated 10 i can belaminated together at the stretched regions 46, while the un-stretchedregions 44 may not be laminated together.

In addition to any compositional differences between layers 10 c, 10 d,10 f, 10 g, or 10 h of a given multi-layer film, the different filmlayers can have differing gauges or thicknesses. In one or moreimplementations, the film layers may be substantially equal to oneanother in thickness. For example, the inventors have found that the MDor TD tear resistance of the composite, multi-layer film is typicallyapproximately equal to the lowest MD or TD tear value of the individuallayers, absent any increase in tear resistance provided by lightbonding. In other words, the weakest layer often determines the strengthof the multi-layer film structure.

As shown by FIGS. 1B and 1C the un-bonded regions 44 of themulti-layered lightly-laminated films 10 e, 10 i, can have a firstaverage thickness or gauge 48 a, 48 b, respectively. The first averagegauge 48 a, 48 b can be approximately equal to the combined startinggauges 42 a-b, 42 c-e of the starting films. In the Figures, separationbetween the unbonded layers at regions 44 is exaggerated for purposes ofclarity. In one or more implementations, the first average gauge 48 a,48 b can be less than the combined starting gauges 42 a-42 b, 42 c-42 e.The lightly bonded regions 46 can have a second average thickness orgauge 50 a, 50 b. In one or more implementations, the second averagegauge 50 a, 50 b can be less than the combined starting gauges 42 a-42b, 42 c-42 e and the first average gauge 48 a, 48 b, respectively.

In any event, FIGS. 1A-1C illustrate that intermeshing rollers 12, 14can process the initially separately layered films into MDincrementally-stretched multi-layered lightly-laminated films. Aspreviously mentioned, the MD incrementally-stretched multi-layeredlightly-laminated films can include a striped pattern 36 where thebonding occurs along a continuous line or region along the width of thefilm 10 b, parallel to the TD direction. The striped pattern 36 caninclude alternating series of un-bonded, un-stretched regions 44 andbonded, stretched regions 46. Although the un-stretched regions of themulti-layered lightly-laminated films may be stretched to a small degreeby rollers 12, 14 (or stretched in a separate operation), theun-stretched regions may be stretched less compared to the bonded,stretched regions 46.

FIG. 2 illustrates a top view of the MD incrementally-stretchedmulti-layered lightly-laminated film 10 b with adjacent bonded andunbonded regions. As shown by FIG. 2, the film 10 b includes bonded,stretched regions 46 adjacent to un-bonded, un-stretched regions 44. Inaddition to resulting in partially discontinuous lamination of adjacentlayers, MD ring rolling the film 10 can increase or otherwise modify oneor more of the tensile strength, tear resistance, impact resistance, orelasticity of the film 10 b, in addition to whatever additional strengthis provided by the partially discontinuous, low strength bonds betweenadjacent layers of the film. Such bonds can be broken to absorb forcesrather than such forces resulting in tearing of the film.

Furthermore, the bonded, stretched regions 46 can include bonded stripesthat extend across the film 10 b in a direction transverse (i.e.,transverse direction) to a direction in which the film was extruded(i.e., machine direction). As shown by FIG. 2, the bonded stripes orstretched regions 46 can extend across the entire length of the film 10b. One will appreciate in light of the disclosure herein that thestriped pattern 36 may vary depending on the method used toincrementally stretch and partially discontinuously bond adjacent layersof film 10. To the extent that MD or other ring rolling is used tolightly bond the film 10, the striped pattern 36 (e.g., width andspacing of the stripes or stretched regions 46) on the film 10 candepend on the pitch 32 of the ridges 24, 26, the DOE 34, and otherfactors. As regions 46 represent areas of the multi-layer film in whichthe adjacent layers are lightly bonded to one another, it will beapparent that altering the spacing and/or width of regions 46 can affectthe overall strength of the film. For example, providing more bondedsurface area relative to the unbonded surface area can increase thedensity of such bonds that can absorb forces, increasing the filmstrength.

FIG. 2 further illustrates that the bonded regions 46 can beintermittently dispersed about un-bonded regions 44. In particular, eachbonded region 46 can reside between adjacent un-bonded regions 44.Additionally, the bonded regions 46 can be visually distinct from theun-bonded regions 44 as a result of stretching. The striped pattern 36may vary depending on the method used to lightly laminate the film 10.In one or more implementations, the molecular structure of thethermoplastic material of the film multi-layered 10 may be rearrangedduring stretching (e.g., particularly so during cold stretching).

MD ring rolling is one exemplary method of partially discontinuouslylaminating a multi-layer film by incremental stretching of the film. TDring rolling is another suitable method of discontinuously or partiallydiscontinuously laminating a film. For example, FIG. 3 illustrates a TDring rolling process that partially discontinuously and lightly bondsadjacent layers of a thermoplastic multi-layer film 10 by passing thefilm 10 through a pair of TD intermeshing rollers 52, 54.

A TD ring rolling process (and associated TD intermeshing rollers 52,54) can be similar to the MD ring rolling process (and associated MDintermeshing rollers 12, 14) described herein above, except that theridges 56, 58 and grooves 60, 62 of the TD intermeshing rollers 52, 54extend generally orthogonally to the axes of rotation 16, 20 (i.e.,parallel to the MD direction). Thus, as shown by FIG. 3, as thethermoplastic film 10 passes between the intermeshing rollers 52, 54,the ridges 56, 58 can incrementally stretch and lightly bond adjacentlayers of the multi-layer film 10. The resultant multi-layeredlightly-laminated film 10 j can include a striped pattern 36 a withadjacent bonded and unbonded regions.

FIG. 4 illustrates a view of the TD incrementally-stretchedmulti-layered lightly-laminated film 10 j with bonded regions 46 a andadjacent un-bonded regions 44 a. The striped pattern 36 a can includealternating series of un-bonded regions 44 a and bonded regions 46 a.Similar to MD ring rolling, TD ring rolling the multi-layered film 10can result in relatively light, partially discontinuous bonding ofadjacent layers 10 c, 10 d (or 10 f, 10 g, 10 h), increasing thestrength of the multi-layer film 10 j.

FIG. 4 illustrates that the bonded regions 46 a can include stripes thatextend across the multi-layered lightly-laminated film 10 j in themachine direction. As shown by FIG. 4, the stripes or bonded regions 46a can extend across the entire width of the multi-layeredlightly-laminated film 10 j. In alternative implementations, bondedregions 46 a can extend across only a portion of the multi-layeredlightly-laminated film 10 j. Similar to MD ring rolling, the pitch andthe DOE of the ridges 56, 58 of the intermeshing rollers 52, 54 canaffect the width and spacing of the stripes or bonded regions 46 a, aswell as the strength of the light bonds formed between adjacent layers,thereby affecting the overall increase in strength provided by theprocessing.

In still further implementations, a multi-layered film 10 can undergoboth an MD ring rolling process and a TD ring rolling process to lightlybond the individual layers together. For example, FIG. 5 illustrates atop view of a multi-layered lightly-laminated film 10 k with bonded,stretched regions separated by un-bonded, un-stretched regions createdby MD and TD ring rolling. The multi-layered lightly-laminated film 10 kcan have a grid pattern 36 b including alternating series of un-bondedregions 44 b and bonded regions 46 b, 46 c. In particular, un-bondedregions 44 b may comprise a plurality of discrete squares or rectangleswhile the remainder of the surface comprises a grid of horizontal andvertical bonded regions that are connected together. The bonded regions46 b, 46 c can include stripes 46 b that extend along the multi-layeredlightly-laminated film 10 k in the machine direction, and stripes 46 cthat extend along the film in the transverse direction, which cross eachother. As shown by FIG. 5, in one or more implementations, the aspectratio of the rows and columns of the bonded regions 46 b, 46 c can beapproximately 1 to 1. In alternative implementations, the aspect ratioof the rows and columns of bonded regions 46 b, 46 c can be greater orless than 1 to 1, for example, as explained in greater detail inrelation to FIG. 13.

The multi-layered lightly-laminated film 10 k with bonded regions andadjacent un-bonded regions created by MD and TD ring rolling can allowfor greater material savings by further increasing the surface area of agiven portion of film, by increasing the density of light laminationbonds within a given area, and may also provide properties or advantagesnot obtained by MD or TD ring rolling alone.

In yet further implementations, a manufacturer can use DD ring rollingto lightly bond a thermoplastic film. DD ring rolling processes (andassociated DD intermeshing rollers) can be similar to the MD ringrolling process (and associated MD intermeshing rollers 12, 14)described herein above, except that the ridges and grooves of the DDintermeshing rollers can extend at an angle relative to the axes ofrotation. For example, FIG. 6 illustrates a view of multi-layeredlightly-laminated film 101 with bonded regions created by DD ringrolling. The multi-layered lightly-laminated film 101 can have a diamondpattern 36 c. The diamond pattern 36 c can include alternating series ofdiamond-shaped un-bonded regions 44 c and bonded regions 46 d. Thebonded regions can include stripes 46 d oriented at an angle relative tothe transverse direction such that the stripes 46 d are neither parallelto the transverse or machine direction. The illustrated configurationmay be achieved with two ring rolling operations, similar to that ofFIG. 5, but in which the DD ring rollers of each operation are angularlyoffset relative to one another (e.g., one providing an angle of about45° off of MD ring rolling, the other providing an angle of about 45°off of TD ring rolling).

In accordance with another implementation, a structural elastic likefilm (SELF) process may be used to create a thermoplastic film withstrainable networks, which similarly results in discontinuous bonding ofadjacent layers within a multi-layer film. As explained in greaterdetail below, the strainable networks can include adjacent bonded andun-bonded regions. U.S. Pat. No. 5,518,801; U.S. Pat. No. 6,139,185;U.S. Pat. No. 6,150,647; U.S. Pat. No. 6,394,651; U.S. Pat. No.6,394,652; U.S. Pat. No. 6,513,975; U.S. Pat. No. 6,695,476; U.S. PatentApplication Publication No. 2004/0134923; and U.S. Patent ApplicationPublication No. 2006/0093766 each disclose processes for formingstrainable networks or patterns of strainable networks suitable for usewith implementations of the present invention. The contents of each ofthe aforementioned patents and publications are incorporated in theirentirety by reference herein.

FIG. 7 illustrates a pair of SELF'ing intermeshing rollers 72, 74 forcreating strainable networks with lightly bonded regions in a film. Thefirst SELF'ing intermeshing roller 72 can include a plurality of ridges76 and grooves 78 extending generally radially outward in a directionorthogonal to an axis of rotation 16. Thus, the first SELF'ingintermeshing roller 72 can be similar to a TD intermeshing roller 52,54. The second SELF'ing intermeshing roller 74 can include also includea plurality of ridges 80 and grooves 82 extending generally radiallyoutward in a direction orthogonal to an axis of rotation 20. As shown byFIG. 7, however, the ridges 80 of the second SELF'ing intermeshingroller 74 can include a plurality of notches 84 that define a pluralityof spaced teeth 86.

Referring now to FIG. 8, a multi-layered lightly-laminated film 10 mwith bonded regions dispersed about un-bonded regions created using theSELF'ing intermeshing rollers 72, 74 is shown. In particular, as thefilm passes through the SELF'ing intermeshing rollers 72, 74, the teeth86 can press a portion of the multi-layer web or film out of plane tocause permanent deformation of a portion of the film in the Z-direction.The portions of the film that pass between the notched regions 84 of theteeth 86 will be substantially unformed in the Z-direction, resulting ina plurality of deformed, raised, rib-like elements 88. The length andwidth of rib-like elements 88 depends on the length and width of teeth86.

As shown by FIG. 8, the strainable network of the multi-layeredlightly-laminated film 10 m can include first un-bonded regions 44 d,second un-bonded regions 44 e, and bonded transitional regions 46 econnecting the first and second un-bonded regions 44 d, 44 e. The secondun-bonded regions 44 e and the bonded regions 46 e can form the raisedrib-like elements 88 of the strainable network. The bonded regions 46 ecan be discontinuous or separated as they extend across themulti-layered film 10 m in both transverse and machine directions. Thisis in contrast to stripes that extend continuously across a film in oneof the machine or transverse directions.

The rib-like elements 88 can allow the multi-layered lightly-laminatedfilm 10 m to undergo a substantially “geometric deformation” prior to a“molecular-level deformation” or a “macro-level deformation.” As usedherein, the term “molecular-level deformation” refers to deformationwhich occurs on a molecular level and is not discernible to the normalnaked eye. That is, even though one may be able to discern the effect ofmolecular-level deformation, e.g., macro-level deformation of the film,one is not able to discern the deformation which allows or causes it tohappen. As used herein, the term “macro-level deformation” refers to theeffects of “molecular-level deformation,” such as stretching, tearing,puncturing, etc. In contrast, the term “geometric deformation,” whichrefers to deformations of multi-layered lightly-laminated film 10 mwhich are generally discernible to the normal naked eye, but do notcause the molecular-level deformation when the multi-layered film 10 mor articles embodying the multi-layered lightly-laminated film 10 m aresubjected to an applied strain. Types of geometric deformation include,but are not limited to bending, unfolding, and rotating.

Thus, upon application of strain, the rib-like elements 88 can undergogeometric deformation before either the rib-like elements 88 or the flatregions undergo molecular-level deformation. For example, an appliedstrain can pull the rib-like elements 88 back into plane with the flatregions prior to any molecular-level deformation of the multi-layeredfilm 10 m. Geometric deformation can result in significantly lessresistive forces to an applied strain than that exhibited bymolecular-level deformation.

In addition to improved properties thus provided by the ability togeometrically deform, the SELF'ing process also discontinuously andlightly laminates adjacent layers of the multi-layer film together,providing the benefits noted above. In particularly, the film layers 11f, 11 g can be lightly laminated at stretched regions 46 e, butun-bonded at the un-stretched regions 44 d and 44 e. The strength of thelamination bond is relatively weak, so as to be less than the weakesttear resistance of the individual layers of the multi-layer film. Thus,the lamination bond is broken rather than the individual layer tearingupon application of a force. Typically, tearing in the MD directionrequires less applied force than tearing in the TD direction, thus inone embodiment, the lamination bond strength is less than the MD tearresistance of each individual layer of the multi-layer film.

FIG. 9 illustrates a multi-layered lightly-laminated film 10 n with astrainable network of rib-like elements 88 a arranged in diamondpatterns. The strainable network of the multi-layered lightly-laminatedfilm 10 n can include first un-bonded regions 44 d, second un-bondedregions 44 e, and bonded transitional regions 46 e connecting the firstand second un-bonded regions 44 d, 44 e.

One or more implementations of the present invention can includestrainable network patterns other than those shown by FIGS. 8 and 9, orcombinations of various patterns. It should be understood that the term“pattern” is intended to include continuous or discontinuous sections ofpatterns, such as may result, for example, from the intersection offirst and second patterns with each other. Furthermore, the patterns canbe aligned in columns and rows aligned in the machine direction, thetransverse direction, or neither the machine or transverse directions.

For example, FIGS. 10A and 10B show a multi-layered lightly-laminatedfilm 10 o where the film layers have undergone a film stretching processin which a discontinuous laminate material is formed with a strainablenetwork of distinct regions. The strainable network laminate includes aplurality of un-bonded areas 146 that define a first region and aplurality of bonded areas 148 that define a second region. Portions ofthe un-bonded areas 146, indicated generally as 147, extend in a firstdirection and may be substantially linear. Remaining portions of theunbonded areas 146, indicated generally as 145, extend in a seconddirection that is substantially perpendicular to the first direction,and the remaining portions 145 of the unbonded areas 146 may besubstantially linear. While it may be preferred that the first directionbe perpendicular to the second direction, other angular relationshipsbetween the first direction and the second direction may be suitable.The angles between the first and second directions may range from about45° to about 135°, with 90° being the most preferred. Intersectingsections of the portions 147 and 145 of the unbonded areas 146 formboundaries 150 (only one shown in FIG. 10A), which completely surroundthe bonded areas 148. It should be understood that the boundaries 150are not limited to the square shape illustrated herein and thatboundaries 150 may comprise other shapes as required by the particularconfiguration of the un-bonded and bonded areas 146, 148, respectively.

The multi-layered lightly-laminated multi-layer film 10 o shown in FIG.10A-10B comprises a multi-directional strainable network laminateproviding stretch characteristics in multiple directions of strain,similar to that shown in FIG. 8. A first region comprises un-bondedareas 146 generally illustrated as bands of unformed material generallylying in a plane defined by the discontinuous laminate material 10 o. Asecond region comprises bonded areas 148 generally defined by nub-likepatterns 152 (see FIG. 10B) extending out of the plane of thediscontinuous laminate material 10 o and comprised of a patternextending in first and second distinct directions as formed by first andsecond superimposed patterns, where the patterns are illustrated asbeing substantially similar to each other.

FIGS. 11A-11B illustrate an embossing type roll configuration forlightly bonding layers together by forming a multi-directionalstrainable network laminate in a single pass through a set ofintermeshing rollers including a punch roll 153 and a cooperating dieroll 154, where the punch roll is provided with punch regions 156 andthe die roll is provided with corresponding die regions 158 forcooperating with the punch regions 156. The punch regions 156 may eachbe provided with a plurality of punch elements 160 for cooperating withcorresponding die elements 162 in the die regions 158. Cooperatingengagement of the punch elements 160 with the die elements 162, with asheet material therebetween, forms a bonded pattern on the material.Alternatively, the cooperating die roll 154 may comprise a conformablesurface for conforming to the punch elements 160, or other surfaceconfiguration of the punch roll 153.

Referring to FIG. 11C, a pattern formed by the rolls 153, 154 isillustrated in which each of the bonded areas 148 of themulti-directional strainable network laminate is formed by a cooperatingset of punch and die elements 160, 162, such as is illustrated in theenlarged surface views of FIG. 22B, and the remaining unformed areasdefine the un-bonded areas 146 of the multi-layered lightly-laminatedfilm including multi-directional strainable networks.

One will appreciate in light of the disclosure herein that using ringrolling and/or SELFing to form the light bonds can provide theadditional benefit of stretching the film layers, thereby reducing thebasis weight of the multi-layered lightly-laminated film. Thus, usingincremental stretching to form the light bonds can allow for multi-layerfilms at a lower basis weight (amount of raw material) to perform thesame as or better than higher basis weight mono-layer or co-extrudedfilms.

In addition to ring rolling and SELFing, one or more implementationsinclude using embossing, stamping, adhesive lamination, ultrasonicbonding, or other methods of lightly laminating layers of a multilayerfilm. In such implementations, one or more of the layers of themulti-layered lightly-laminated film can be stretched to reduce thebasis weight and/or modify the strength parameters of the film prior tolamination. Stretching of the individual layers can includeincrementally-stretching (e.g., ring rolling, SELFing) or continuousstretching (e.g., MDO).

One will appreciate in light of the disclosure herein that the lightlybonded multi-layered films can form part of any type of product madefrom, or incorporating, thermoplastic films. For instance, grocery bags,trash bags, sacks, packaging materials, feminine hygiene products, babydiapers, adult incontinence products, sanitary napkins, bandages, foodstorage bags, food storage containers, thermal heat wraps, facial masks,wipes, hard surface cleaners, and many other products can includelightly bonded multi-layer films to one extent or another. Trash bagsand food storage bags may be particularly benefited by the films andmethods of the present invention.

Referring to FIGS. 12A and 12B, a flexible draw tape multi-layered bag90 of one or more implementations of the present invention is shown. Themulti-layered bag 90 can include a bag body 92 formed from two pieces ofthermoplastic film 10 p and 10 q folded along a bag bottom 94. Sideseams 96 and 98 can bond the sides of the bag body 92 together to form asemi-enclosed container having an opening 100 along an upper edge 102.The multi-layered bag 90 also optionally includes closure means 104located adjacent to the upper edge 102 for sealing the top of themulti-layered bag 90 to form a fully-enclosed container or vessel. Themulti-layered bag 90 is suitable for containing and protecting a widevariety of materials and/or objects. In alternative implementations, inplace of a draw tape, the closure means 104 can comprise flaps, adhesivetapes, a tuck and fold closure, an interlocking closure, a sliderclosure, a zipper closure or other closure structures known to thoseskilled in the art for closing a bag.

As shown by FIGS. 12A and 12B, the multi-layered bag 90 can have a firstlayer of thermoplastic material (i.e., film 10 p). The first layer(i.e., film 10 p) can include first and second side walls joined along abottom edge, a first side edge, and an opposing second side edge. Inparticular, the bottom edge of the first layer (i.e., film 10 p) cancomprise a fold. The multi-layered bag 90 can also include a secondlayer of thermoplastic material (i.e., film 10 q). The second layer(i.e., film 10 q) can include first and second side walls joined along abottom edge, a first side edge, and an opposing second side edge.

As shown by FIG. 12B, the second layer (i.e., film 10 q) is positionedwithin the first layer (i.e., film 10 p). Furthermore, the first layer(i.e., film 10 p) and the second layer (i.e., film 10 q) arenon-continuously bonded to each other as described below. Furthermore,in the implementation shown in FIGS. 12A and 12B, both the first layer(i.e., film 10 p) and the second layer (i.e., film 10 q) areincrementally stretched.

Such a configuration may be considered a “bag-in-bag” configuration. Inother words the multi-layered bag 90 can include a second thermoplasticbag 10 q positioned within a first thermoplastic bag 10 p. Each of thefirst and second bags 10 p, 10 q can include a first pair of opposingsidewalls joined together along three edges. A plurality ofnon-continuous bonded regions can secure the first and secondthermoplastic bags together.

In particular as shown by FIG. 12A, the multi-layered bag 90 can includediscrete zones of non-continuous lamination between the layers 10 p, 10q. In particular, the multi-layered bag 90 includes a first, top section116 that is adjacent the opening 100 and a second, bottom section 120that is adjacent the bottom edge or fold 94. The top section 116 of themulti-layered bag 90 can include bonded regions interspersed withun-bonded regions. In particular, FIG. 12A illustrates that the topsection 116 can include strainable network bonds 101 (i.e., bondscreated by a SELFing process) arranged in diamond patterns similar tothe multi-layered lightly-laminated film 10 n of FIG. 9. The strainablenetwork bonds 101 can discontinuously bond the layers 10 p and 10 qtogether in the top section 116.

The bottom section 120 on the other hand can include non-continuousbonds 46 a created by TD ring rolling. In particular, the bottom section120 can include un-bonded regions 44 a and bonded regions 46 a in theform of stripes. The stripes can extend across the multi-layered bag 90in the MD direction, or in other words, from the first side seam 96 tothe second side seam 98.

One will appreciate in light of the disclosure herein that the differenttypes of non-continuous bonds in the top and bottom sections 116, 120can provide the different strength and aesthetic properties to the topand bottom sections 116, 120. For example, the non-continuous bonds 46 acreated by TD ring rolling can provide the bottom section 120 withincreased MD tear resistance, balanced MD and TD resistances, and/orincreased the impact and/or puncture resistance. Additionally, the TDring rolling of the bottom section 120 can result in reduced materialutilization. The strainable network bonds 101 can provide the topsection 116 with the ability to stretch around objects and prevent tearsand rips. In other implementations, the inner and outer bags can benon-continuously laminated together through the use of TD ring rolling,DD, ring rolling, SELFing, ultrasonic bonding, adhesive bonding, or anycombination of such various bonding techniques.

Thus, one or more implementations allow for the tailoring of variouszones or sections of a multi-layered bag with different non-continuousbonds or bonded regions. In particular, different types, sizes, shapes,patterns, concentrations, and/or combinations of non-continuous bondscan provide different zones or sections of a multi-layered bag withstrength and/or aesthetic properties optimal for the particular zone orsection. FIG. 12A illustrates a multi-layered bag 90 with two zones. Onewill appreciate that the present invention is not so limited andmulti-layered bags of one or more implementations can include 2, 3, 4,5, 6, or more zones or sections with tailored non-continuous bonds.Furthermore, the Figs. illustrate sections that extend along the widthof the bag (i.e., bottom, middle, and upper), in alternativeimplementations, the sections can extend across the height of the bag(i.e., left side, middle, right side). In still further implementationsthe sections can comprise a combination of width-wise and length-wiseextending sections. Alternatively, the sections are neither width-wisenor length-wise extending. For example, the sections can extend at anangle to the edges of the bag.

FIG. 13 illustrates a multi-layered tie bag 106 with discretenon-continuous lamination in accordance with an implementation of thepresent invention. In particular, the multi-layered tie bag 106 includesan outer film 10 r non-continuously bonded to an inner film 10 s indiscrete sections or zones. In particular, a plurality of strainablenetwork bonds 101 can non-continuously bond the outer film 10 r to theinner film 10 s in the bottom section 120. On the other hand, aplurality of non-continuous bonds 46 f formed from TD ring rolling cannon-continuously bond the outer film 10 r to the inner film 10 s in theupper section 116.

The bonded regions 46 f and 101 are characterized by relatively lightbonding of adjacent layers 10 r, 10 q of the multi-layer bag 106, whichacts to absorb forces into breaking of the lamination bond rather thanallowing that same force to cause tearing of either of the layers of themulti-layer bag 106. Such action provides significantly increasedstrength to the multi-layer film as compared to a monolayer similarthickness film or compared to a multi-layer film of similar thicknesswhere the layers are strongly bonded together (i.e., at a bond strengthat least as great as the tear resistance of the weakest layer). Thelamination bond includes a bond strength that is advantageously lessthan the tear resistance of each of the individual films so as to causethe lamination bond to fail prior to tearing of the film layers.

In addition to non-continuous bonding, one or more layers of themulti-layered bags of one or more implementations can be incrementallystretched. One will appreciate that some types of non-continuous bondingdescribed here can incrementally stretch the layers as they arenon-continuously bonded (i.e., ring rolling, SELFing). One or moreimplementations of the present invention further include incrementallystretching one or more layers independent of bonding. For example, theouter layer 10 r of the multi-layer bag 106 of FIG. 13 is a MDincrementally stretched film, similar to film 10 b of FIG. 2. The MDincrementally stretched film 10 r is then non-continuously laminated tothe inner layer 10 s as described above.

In comparison with the film 10 k of FIG. 5, the spacing between the MDextending bonds 46 f is greater in the multi-layered bag 106. Thiseffect is created by using TD ring rolls having a greater pitch betweenridges. Similarly, the spacing of the TD extending stripes 46 g isgreater in the multi-layered bag 106 than the multi-layered film 10 m.This effect is created by using TD ring rolls having a greater pitchbetween ridges. Furthermore, the relative spacing between the MDextending stripes and the TD extending stripes differs in themulti-layered bag 106, while relative spacing is the same in themulti-layered film 10 k. This effect is created by using TD ring rollshaving a greater pitch between ridges compared to the pitch betweenridges of the MD ring rolls.

One will appreciate in light of the disclosure herein that the use ofintermeshing rollers with greater or varied ridge pitch can provide thedifferent spacing and thicknesses of the stripes. Thus, a manufacturercan vary the ridge pitch of the intermeshing rollers to vary the patternof the multi-layer film. The bond density (i.e., the fraction of surfacearea that is bonded relative to unbonded) and particular patternprovided not only affects the aesthetic appearance of the bag or film,but may also affect the strength characteristics provided. For example,higher bond density may provide increased strength as it provides agreater number of relatively low strength lamination bonds that may bebroken so as to absorb forces, preventing such forces from leading totearing of the bag or film. Film 10 k of FIG. 5 has a higher bonddensity than the film of the bag 106 of FIG. 13.

By way of further example, where the MD tear resistance is lower than TDtear resistance for the particular films employed, it may beadvantageous to provide a higher density of bonds in the MD than the TDdirection. This may provide greater improvement to MD tear resistance ofthe multi-layered lightly-laminated film as compared to TD tearresistance improvement. A similar configuration could be provided forfilms in which the TD tear resistance were lower than MD tear resistanceby increasing bond density in the TD direction.

In addition to varying the pattern of bonded and un-bonded regions in abag or film, one or more implementations also include providing lightlybonded regions in certain sections of a bag or film, and only un-bonded(or alternatively tightly bonded) regions in other sections of the bagor film. For example, FIG. 14 illustrates a multi-layered bag 114 havingan upper section 116 adjacent a top edge 118 that is devoid of bondedregions. Similarly, the multi-layered bag 114 includes a bottom section120 adjacent a bottom fold or edge 122 devoid of bonded regions. Inother words, both the top section 116 and bottom section 120 of themulti-layered bag 114 can each consist only of un-bonded regions.Alternatively, the layers of sections 116 and 120 may be tightly bondedtogether (e.g., co-extruded). In any case, sections 116 and 120 may bevoid of bonds.

A middle section 124 of the multi-layered bag 114 between the upper andlower sections 116, 120 on the other hand can include lightly bondedregions interspersed with un-bonded regions. In particular, FIG. 14illustrates that the middle section can include a strainable network ofrib-like elements arranged in diamond patterns similar to themulti-layered lightly-laminated film 10 n of FIG. 9. Thus, the middlesection 124 of the multi-layered bag 114 can include improved strengthcreated by the light bonds of the strainable network.

As mentioned previously, one or more implementations of the presentinvention includes providing different lightly bonded regions indifferent sections of a bag or film. For example, FIG. 15 illustrates amulti-layered bag 114 a similar to the multi-layered bag 114 of FIG. 14,except that the bottom section 120 a includes alternating series ofun-bonded regions 44 a and bonded regions 46 a created by TD ringrolling. Thus, the middle section 124 of the bag 114 can includeproperties of increased strength as a result of light discontinuouslamination and increased elasticity through geometric deformation, whilethe bottom section includes increased strength as a result of lightpartially discontinuous lamination by TD ring rolling.

FIG. 16 illustrates yet another multi-layered bag 126 including an uppersection 116 a adjacent a top edge 118 that includes alternating seriesof un-bonded regions 44 b and bonded regions 46 b, 46 c created by MDand TD ring rolling similar to the film 10 k of FIG. 5. Furthermore, themiddle section 124 a of the multi-layered bag 126 can include un-bondedregions 44 and bonded regions 46 in the form of stripes created by MDring rolling.

Thus, one will appreciate in light of the disclosure herein that amanufacturer can tailor specific sections or zones of a bag or film withdesirable properties by MD, TD, DD ring rolling, SELF'ing, orcombinations thereof. One will appreciate in light of the disclosureherein that one or more implementations can include bonded regionsarranged in other patterns/shapes. Such additional patterns include, butare not limited to, intermeshing circles, squares, diamonds, hexagons,or other polygons and shapes. Additionally, one or more implementationscan include bonded regions arranged in patterns that are combinations ofthe illustrated and described patterns/shapes.

FIGS. 17-25 illustrate additional exemplary implementations ofmulti-layer bags that may be formed from multi-layered lightly-laminatedfilms. FIGS. 17-19 and 25 illustrate additional examples of bags 127including squares 128, diamonds 130, and circles 132 representing thebonded areas of the two or more adjacent layers. In one or moreimplementations, such as FIGS. 17-18 and 23, each bonded pattern mayhave a largest TD patterned width 134 in the transverse direction (TD)of less than about 25% of the transverse width 136 of the patternedfilm, or less than about 20% of the transverse width of the film, orless than about 10% of the transverse width of the patterned film, orless than about 5% of the transverse width of the film. In one or moreimplementations, the bonded patterns should have a largest MD patternedwidth 138 in the machine direction of less than about 25% of the machinewidth 140 of the patterned film, or less than about 20% of the machinewidth of the film, or less than about 10% of the machine width of thefilm, or less than about 5% of the transverse width of the film.

In one or more implementations, the width 134 of the bonded patterns inthe transverse direction may be greater than the width 142 of theun-bonded areas in the transverse direction. The width 138 of the bondedpatterns in the machine direction or direction perpendicular to thetransverse direction may be greater than the width of the un-bondedareas 144 in the machine direction.

The bond density of the multi-layered lightly-laminated films and bagsincorporating the same can be varied to control the bond strengthbetween the layers. For example, bonded areas of multi-layeredlightly-laminated films and bags incorporating the same can be large incomparison to un-bonded areas, as seen in the implementations of FIGS.17-18 and 25. For example, bonded areas of multi-layeredlightly-laminated films and bags incorporating the same can represent atleast about 50% of the total area of the entire film, the entire bag, orthe section where the lamination occurs, or at least about 60% of theentire film, the entire bag, or total area of the section where thelamination occurs, at least about 70% of the entire film, the entirebag, or total area of the section where the lamination occurs, at leastabout 80% of the total area of the entire film, the entire bag, orsection where the lamination occurs. In other embodiments, for examplein FIGS. 19-20, the bonded areas of multi-layered lightly-laminatedfilms and bags incorporating the same can represent substantially lessthan about 50% of the total area of the entire film, the entire bag, orsection where the lamination occurs, or less than about 40% of the totalarea of the entire film, the entire bag, or section where the laminationoccurs, or less than about 30% of the total area of the entire film, theentire bag, or section where the lamination occurs, or less than about10% of the total area of the entire film, the entire bag, or sectionwhere the lamination occurs.

As mentioned previously, numerous methods can be used to provide thedesired degree of lamination in the bonded areas. Any of the describedring rolling techniques may be combined with other techniques in orderto further increase the strength of the lamination bond whilemaintaining bond strength below the strength of the weakest layer of themulti-layer film. For example, heat, pressure, ultrasonic bonding,corona treatment, or coating (e.g., printing) with adhesives may beemployed. Treatment with a corona discharge can enhance any of the abovemethods by increasing the tackiness of the film surface so as to providea stronger lamination bond, but which is still weaker than the tearresistance of the individual layers.

Adjusting (e.g., increasing) the strength of the relatively lightlamination bonding could be achieved by addition of a tackifier oradhesive to one or more of the skin plies of a multi-layer film, or byincorporating such a component into the material from which the filmlayer is formed. For example, the outer skin sublayers of a given layercould contain from about 0 to about 50% of a polyolefin plastomertackifier such as a C₄-C₁₀ olefin to adjust bonding strength byincreasing the tackiness of the surfaces of adjacent layers to belightly laminated.

In one or more implementations, a component may be included to decreasetackiness. For example, the outer skin sublayers could contain higherlevels of slip or anti-block agents, such as talc or oleamide (amide ofoleic acid), to decrease tack. Similarly, these surfaces may includevery low levels of or be substantially void of slip or anti-block agentsto provide a relative increase in tackiness.

FIG. 18 shows a multi-layer bag 127 including a top section that hasbeen both MD and TD ring rolled, while the bottom section has not beendiscontinuously laminated. FIG. 19 shows a bag 127 including arelatively low density of bonded circles 132 arranged over substantiallythe entire surface of bag 127. FIG. 20 shows a bag 127 including an evenlower density of bonded diamonds near top and bottom sections of bag127. FIG. 21 shows a multi-layer bag 127 that has been ring rolled nearthe top and bottom of the bag. The middle section of the bag representsan un-bonded region between the ring top and bottom portions of bag 127.FIG. 22 shows a bag 127 similar to that of FIG. 21 but in which thebottom section is un-bonded. FIG. 23 shows a bag 127 similar to that ofFIG. 21, but in which the top section includes squares of bonded regionsrather than being ring rolled. FIG. 24 is similar to the bag of FIG. 20,but in which the bonded ring rolled portions along the top arediscontinuous. FIG. 25 shows a multi-layer bag 127 including top andbottom sections that have been DD ring rolled, while a middle sectiontherebetween has not been discontinuously laminated

In another implementation, a pattern may be formed by embossing, in aprocess similar to ring rolling. Embossed patterns such as squares,diamonds, circles or other shapes may be embossed into a multi-layerfilm such as shown in FIGS. 17-20, and 25. The embossed, laminated filmlayers may be prepared by any suitable means by utilizing two or morelayers of preformed web of film and passing them between embossingrollers. The method of embossing multiple layers of film can involvecalendar embossing two or more separate, non-laminated layers withdiscrete “icons” to form bonded areas or icons, each icon having abonded length and separated from adjacent icons by an equivalentun-bonded length. Such icons may be any desired design or shape, such asa heart, square, triangle, diamond, trapezoid, or circle. In FIG. 18,the embossed icons are squares.

Implementations of the present invention can also include methods offorming multi-layered lightly-laminated film and bags including thesame. FIGS. 26-28 and the accompanying description describe suchmethods. Of course, as a preliminary matter, one of ordinary skill inthe art will recognize that the methods explained in detail herein canbe modified. For example, various acts of the method described can beomitted or expanded, additional acts can be included, and the order ofthe various acts of the method described can be altered as desired.

FIG. 26 illustrates an exemplary embodiment of a high-speedmanufacturing process 164 for creating multi-layered thermoplasticfilm(s) with discrete non-continuous lamination and then producingmulti-layered plastic bags with discrete non-continuous laminationtherefrom. According to the process 164, a first thermoplastic filmlayer 10 c and a second thermoplastic film layer 10 d are unwound fromroll 165 a and 165 b, respectively, and directed along a machinedirection.

The film layers 10 c, 10 d may pass between first and second cylindricalintermeshing rollers 166, 167 to incrementally stretch and lightlylaminate the initially separate film layers 10 c, 10 d to createun-bonded regions and bonded regions in a middle section of amulti-layered discretely laminated film 168. As shown in FIG. 26, theintermeshing rollers 166, 167 can be TD intermeshing rollers similar tothe intermeshing rollers 52, 54 of FIG. 3. Alternatively, theintermeshing rollers 166, 167 can comprise embossing or SELFing rollers.In still further implementations, in place of the intermeshing rollers166, 167 the process can include an adhesive applicator or ultrasonichorn that can form adhesive or ultrasonic bonds.

Returning to FIG. 26, the rollers 166, 167 may be arranged so that theirlongitudinal axes are perpendicular to the machine direction.Additionally, the rollers 166, 167 may rotate about their longitudinalaxes in opposite rotational directions as described in conjunction withFIG. 1A. In various embodiments, motors may be provided that powerrotation of the rollers 166, 167 in a controlled manner. As the filmlayers 10 c, 10 d pass between the first and second rollers 166, 167,the ridges and/or teeth of the intermeshing rollers 166, 167 can form amulti-layered discretely laminated film 168.

Optionally, the multi-layered discretely laminated film 168 may thenpass through another lamination process to discretely, non-continuouslylaminate another section or zone of the multi-layered discretelylaminated film 168 together. For example, FIG. 26 illustrates that themulti-layered discretely laminated film 168 can pass between another setof intermeshing rollers 194, 195. The intermeshing rollers 194, 195 cannon-continuously laminate the one or additional sections of themulti-layered discretely laminated film 168 together. As shown in FIG.26, the intermeshing rollers 194, 195 can comprise embossing rollers oralternatively any other of the intermeshing rollers describedhereinabove. Alternatively, a single set of intermeshing rollers canlaminate multiple sections of two or more films together. For example,the ridges and/or teeth of the intermeshing rollers 166, 167 andintermeshing rollers 194, 195 can be combined into a single set ofintermeshing rollers that discretely laminate different sections of twoor more films together using different types of bonding. In yet furtherimplementations, an adhesive applicator or ultrasonic horn can be usedin place of intermeshing rollers 194, 195 to create non-continuous bondsin one or more sections.

During the manufacturing process 164, the multi-layered discretelylaminated film 168 can also pass through a pair of pinch rollers 169,170. The pinch rollers 169, 170 can be appropriately arranged to graspthe multi-layered discretely laminated film 168.

A folding operation 171 can fold the multi-layered discretely laminatedfilm 168 to produce the sidewalls of the finished bag. The foldingoperation 171 can fold the multi-layered discretely laminated film 168in half along the transverse direction. In particular, the foldingoperation 171 can move a first edge 172 adjacent to the second edge 173,thereby creating a folded edge 174. The folding operation 171 therebyprovides a first film half 175 and an adjacent second web half 176. Theoverall width 177 of the second film half 176 can be half the width 177of the pre-folded multi-layered discretely laminated film 168.

To produce the finished bag, the processing equipment may furtherprocess the folded multi-layered discretely laminated film 168. Inparticular, a draw tape operation 178 can insert a draw tape 179 intoends 172, 173 of the multi-layered discretely laminated film 168.Furthermore, a sealing operation 180 can form the parallel side edges ofthe finished bag by forming heat seals 181 between adjacent portions ofthe folded multi-layered discretely laminated film 168. The heat seal181 may strongly bond adjacent layers together in the location of theheat seal 181 so as to tightly seal the edges of the finished bag. Theheat seals 181 may be spaced apart along the folded multi-layereddiscretely laminated film 168 to provide the desired width to thefinished bags. The sealing operation 180 can form the heat seals 181using a heating device, such as, a heated knife.

A perforating operation 182 may form a perforation 183 in the heat seals181 using a perforating device, such as, a perforating knife. Theperforations 183 in conjunction with the folded outer edge 174 candefine individual multi-layered bags with discrete non-continuouslamination 184 that may be separated from the multi-layered discretelylaminated film 168. A roll 185 can wind the multi-layered discretelylaminated film 168 embodying the finished bags 184 for packaging anddistribution. For example, the roll 185 may be placed into a box or bagfor sale to a customer.

In still further implementations, the folded multi-layered discretelylaminated film 168 may be cut into individual bags along the heat seals181 by a cutting operation. In another implementation, the foldedmulti-layered discretely laminated film 168 may be folded one or moretimes prior to the cutting operation. In yet another implementation, theside sealing operation 180 may be combined with the cutting and/orperforation operations 182.

One will appreciate in light of the disclosure herein that the process164 described in conjunction with FIG. 26 can be modified to omit orexpand acts, vary the order of the various acts, or otherwise alter theprocess, as desired. For example, three or more separate film layers canbe discontinuously laminated together to form a multi-layered discretelylaminated film 168 similar to that shown in FIG. 1C.

FIG. 27 illustrates another manufacturing process 186 for producing aplastic bag from a multi-layered discretely laminated film. The process186 can be similar to process 164 of FIG. 26, except that the filmlayers 10 c, 10 d are folded in half to form c-, u-, or j-folded filmsprior to winding on the rolls 165 a, 165 b. Thus, in suchimplementations, the films 10 c, 10 d unwound from the rolls 165 a, 165b are already folded.

Additionally, the manufacturing process 186 illustrates that each film10 c, 10 d can pass through a set of intermeshing rollers 166 a, 167 a,166 b, 166 b to incrementally stretch the films prior to bonding. Themanufacturing process 186 can then include an insertion operation 187for inserting the folded film 10 d into the folded film 10 c. Insertionoperation 187 can combine and laminate the folded films 10 c, 10 d usingany of the apparatus and methods described in U.S. patent applicationNos. 13/225,930 filed Sep. 6, 2011 and entitled Apparatus For InsertingA First Folded Film Within A Second Folded Film and 13/225,757 filedSep. 6, 2011 and entitled Method For Inserting A First Folded FilmWithin A Second Folded Film, each of which are incorporated herein byreference in their entirety.

Additionally, FIG. 27 illustrates that the film layers 10 c, 10 d canthen pass through a lamination operation 188 to lightly bond or laminatethe films 10 c, 10 d together. Lamination operation 188 can lightlylaminate the folded films 10 c, 10 d together via adhesive bonding,pressure bonding, ultrasonic bonding, corona lamination, and the like.Alternatively, lamination operation can lightly laminate the foldedfilms 10 c, 10 d together by passing them through machine-direction ringrolls, transverse-direction ring rolls, diagonal-direction ring rolls,SELF'ing rollers, embossing rollers, or other intermeshing rollers.Furthermore, the lamination operation 188 can laminate one or moresections of the film with a first plurality of non-continuous bonds andone or more additional sections with a second plurality ofnon-continuous bonds. The second plurality of non-continuous bonds candiffer from the first plurality of non-continuous bonds.

FIG. 28 illustrates another manufacturing process 190 for producing amulti-layered lightly-laminated film and a multi-layered bag therefrom.The process 190 can be similar to process 164 of FIG. 25, except thateach film layer 10 c and 10 d may be run through intermeshing rollers(e.g., MD ring rollers) 166, 167 and 166 a, 167 a, respectively, priorto discontinuous lamination of layers 10 c and 10 d to one another.Similar to process 164 of FIG. 25, layers 10 c and 10 d may then benon-continuously laminated together in discrete sections by passingthrough intermeshing rollers 192, 193.

I. Examples

Multi-layered lightly-laminated films according to the present inventionwere formed according to various ring rolling processes. Table I belowlists various discontinuously laminated films and comparative films thatwere tested. Table II lists the physical properties of the films ofTable I. The results recorded in Table II indicate that the bi-layerfilms that were lightly bonded together with discontinuous laminationexhibit significantly improved strength properties, such as the energyto maximum load (Dynatup Max), which relates to impact resistance. Themelt index of the layers of the films were determined under ASTM D-1238,Condition E. It is measured at 190° C. and 2.16 kilograms and reportedas grams per 10 minutes.

TABLE I Discontinuously Laminated Films Discontinuous Gauge Film Layer 1Process Layer 2 Process Lamination (Mils) A LLDPE 0.40 B LDPE 0.40 CHDPE 0.40 D LLDPE Yes 0.40 E LDPE Yes 0.40 F HDPE Yes 0.40 G LLDPE LLDPEYes 0.80 H LDPE LDPE Yes 0.80 I HDPE HDPE Yes 0.80 J LLDPE TD RR LDPE TDRR Yes 0.80 K LLDPE TD RR HDPE TD RR Yes 0.80 L LDPE TD RR HDPE TD RRYes 0.80 M LLDPE MD RR LLDPE TD RR Yes 0.80 N LLDPE MD RR LDPE TD RR Yes0.80 O LLDPE MD RR HDPE TD RR Yes 0.80 LLDPE has a density of 0.920 anda Melt Index of 1.000. LDPE has a density of 0.926 and a Melt Index of0.800. HDPE has a density of 0.959 and a Melt Index of 0.057. TD RR isTD ring rolling at 40 Pitch. MD RR is MD ring rolling at 60 Pitch.Discontinuous Lamination was achieved through SELF'ing at a DOE of0.038″.

TABLE II Physical Properties Tear Yield Peak Load Strain@BreakDynatupEnergy Film MD TD MD TD MD TD MD TD to max. load A 165 274 0.660.64 3.44 1.59 532 606 3.10 B 72 283 0.81 0.86 3.72 2.28 482 660 0.25 C3 314 1.74 0.86 3.83 0.89 268 135 N.A. D 181 176 0.55 0.60 1.21 1.44 352557 3.20 E 175 197 0.70 0.75 1.46 1.21 331 473 1.71 F 12 170 0.30 3.131.70 0.70 115 64 0.45 G 372 427 1.12 1.25 2.92 2.59 389 551 5.81 H 312375 1.39 1.54 2.83 2.39 346 518 3.60 I 14 220 1.20 0.44 2.71 1.07 112 780.87 J 392 385 1.21 1.40 3.19 2.71 385 540 4.15 K 191 292 1.75 1.27 2.621.53 61 535 3.32 L 158 288 2.20 1.50 3.00 1.55 252 498 2.63 M 539 3681.26 1.26 3.32 3.06 456 401 7.19 N 544 383 1.27 1.69 2.18 2.91 365 3626.96 O 574 189 1.44 3.87 1.74 3.87 404 157 1.41 Control 225 625 1.461.43 6.29 4.36 476 665 Tear in grams. Yield in Lb_(f) Peak Load inLb_(f) Strain@Break in % Dynatup Energy to Max in In-Lb_(f) Control is0.9 Mil LDPE film

As shown in Table III, another set of films was evaluated with differentlevels of stretch processes with and without discontinuous lamination ofadjacent layers. The results show significantly increased values ofDynatup Energy to maximum load as a result of discontinuous lamination.

TABLE III Additional Examples Dynatup Gauge Gauge Layer 1 Layer 2Discontinuous Energy to Initial Final Film Process Process Laminationmax. load (mils) (mils) P None None Yes 18.3 2.14 2.12 Q MD-1 TD-1 No7.2 2.14 1.92 R MD-1 TD-1 Yes 17.1 2.14 1.93 S MD-2 TD-2 No 8.7 2.141.68 T MD-2 TD-2 Yes 15.3 2.14 1.63 Base None None No 5 1.07 1.07

As shown in Table IV, samples of cold processed MD ring rolled (at0.100″ DOE, 0.100″ pitch, LDPE film were laminated under a cold ringrolling process to achieve unexpectedly superior tear resistanceproperties. The MD Tear and the TD Tear resistance values weresynergistically enhanced as a result of the discontinuous laminationprocess. Bond strength could be further increased while still being lessthan the strength of the weakest layer by addition of a tackifier, anadhesive, corona treatment, etc. to increase tackiness between thelayers.

TABLE IV Ring Rolled Laminates Sample MD Tear TD Tear TD ring rolledlaminate of A and B, 21.5 gsm^(a) 429 881 A. MD ring rolled, Black toplayer^(b) 193 580 B. MD ring rolled, White bottom layer^(c) 261 603 TDring rolled laminate of C and D, 18.8 gsm 314 876 C. MD ring rolled,Black top layer^(d) 170 392 D. MD ring rolled, Black bottom layer^(d)151 470 TD ring rolled laminate of E and F, 21.1 gsm 312 1018 E. MD ringrolled, Black top layer^(b) 218 765 F. MD ring rolled, Black bottomlayer^(d) 170 387 ^(a)TD ring rolling was 0.040″ pitch tooling run at0.020″ DOE. The A and B webs were simultaneously run first through theMD and then the TD tooling. ^(b)14 gsm 3 ply coextruded black layer withouter skin plies containing 30% DOW Affinity ™ 8100 and 2% talc,processed at blowup ratio A and MD ring rolled. MD ring rolling was0.100″ pitch tooling run at 0.100″ DOE. ^(c)14 gsm 3ply coextruded whitelayer with 2% slip agent in outer skin plies, processed at blowup ratio1.5A and MD ring rolled at 0.100″ pitch tooling run at 0.100″ DOE.^(d)14 gsm 3 ply coextruded black layer with outer skin plies containing30% DOW Affinity ™ 8100 and 2% talc, processed at blowup ratio 1.5A andMD ring rolled at 0.100″ pitch tooling run at 0.100″ DOE.

The MD and TD tear values shown in Table IV show how the MD tear valueis significantly increased relative to the MD tear value of theindividual layers. The data shows an additive or synergistic effect inboth MD and TD tear resistance. For example, Example A exhibits an MDtear resistance of 193 g-f, while Example B exhibits an MD tearresistance of 261 g-f. When both layers are lightly laminated togetherby TD ring rolling, the MD tear resistance is 429 g-f. This is nearly asgreat as the additive strength of the two layers, which would be 454g-f. Such results are particularly surprising and advantageous, as whenthe two layers are tightly laminated together (e.g., co-extruded), thestrength of the composite film typically reverts to the have a strengthapproximately equal to that of the weakest layer (i.e., about 193 g-f).Thus, the light, discontinuous lamination of adjacent layers into amulti-layer film provides significant increases in strength.

Examples A through F were each discontinuously laminated by MD ringrolling at a pitch of 0.100″, a DOE of 0.100″, and simultaneously TDring rolling at a pitch of 0.040″ and a DOE of 0.020″.

In another example, a first layer of a base film having a core ply ofLLDPE with white pigment and outer plies of LLDPE\LDPE\Antiblock blendwas cold MD ring rolled to form an MD ring rolled (RR) film. The MDintermeshing rolls used in Example 1 had a 0.100″ pitch and were set ata DOE of 0.110″. A second layer of the base film was cold TD ring rolledto form a TD RR film. The TD intermeshing rolls used in Example 1 had a0.060″ pitch and were set at a DOE of 0.032″. The MD RR film and the TDRR film were then laminated together using a butene-1-copolymer, hotmelt adhesive, Rextac® RT 2730 at four different coat weights shown inTable V as samples 1-4. Table V also shows comparative properties of thebase film, the MD RR film, the TD RR film, the combined MD RR and TD RRfilms not adhesively laminated together, as well as a thicker film.

TABLE V Dynatup and Tear Resistance of Incrementally-StretchedAdhesively- Laminated Films (1 layer MD RR and 1 layer TD RR) CoatDynatup Dynatup Weight Gage Tensile Peak Energy to MD TD g/sq. by Wt.Peel Load max load Tear Tear ft. (mils) (g-f) (lb-f) (in. lb-f) (g) (g)Sample 1 0.225 0.84 N/A 11.3 8.4 434 585 Sample 2 0.056 0.84 N/A 11.111.2 496 539 Sample 3 0.015 0.84 61 10.5 9.2 387 595 Sample 4 0.012 0.8457 11.3 10.4 425 643 Comparison Data Un-laminated NA 0.84 N/A 9.4 6.9326 502 Combined MD and TD RR Films TD RR Film NA 0.4 N/A 4.6 4.4 101 60MD RR Film NA 0.44 N/A 5.4 4.8 173 475 Base Film NA 0.6 N/A 5.1 6.3 298473 Thicker Base NA 0.9 NA 4.3 3.8 262 843 Film

The results from Table V show that even with very low adhesive coating,superior Dynatup, MD tear resistance, and TD tear resistance propertiesare achieved compared to two layers of non-laminated film or one layerof thicker film. In particular, the results from Table V show adhesivelylaminating an MD RR film and a TD RR film can balance the MD and TD tearresistance. Furthermore, the individual values for the Dynatup, MD tearresistance, and TD tear resistance properties are unexpectedly higherthan the sum of the individual layers. Thus, the incrementally-stretchedadhesively-laminated films provide a synergistic effect.

More specifically, as shown by the results from Table V, the TD tearresistance of the incrementally-stretched adhesively-laminated films canbe greater than a sum of the TD tear resistance of the individuallayers. Similarly, the MD tear resistance of the incrementally-stretchedadhesively-laminated films can be greater than a sum of the MD tearresistance of the individual layers. Along related lines, the Dynatuppeak load of the incrementally-stretched adhesively-laminated films canbe greater than a sum of a Dynatup peak load of the individual layers.

TABLE VI Properties of Incrementally-Stretched Adhesively- LaminatedFilms (both layers MD and TD RR) Coat Gage Dynatup Dynatup Dart Wt. byCaliper Tensile Peak Energy to Drop MD TD g/sq. Wt. 1″ Foot Peel Loadmax load F50 Tear Tear ft. (mils) (mils) (g-f) (lb-f) (in. lb-f) (g) (g)(g) Sample 5 0.0300 0.64 1.71 81.5 11.5 11.28 254.0 418 511 Sample 60.0150 0.65 1.85 25.5 10.3 9.61 349 441 Sample 7 0.0100 0.67 1.81 27.610.6 9.34 264.0 353 406 Sample 8 0.0075 0.66 1.79 2.27 9.7 10.99 335 423Sample 9 0.0060 0.66 1.87 7.79 9.9 12.21 260.0 319 450 Comparison DataThicker NA 0.9 0.88 NA 4.3 3.8 180 262 843 Base Film

The results from Tables VI show that even with very low adhesivecoating, superior Dynatup, MD tear resistance, and TD tear resistanceproperties are achieved compared to two layers of non-laminated film orone layer of thicker film. Additionally, the results from Tables VI inconjunction with the Comparison Data from Table V show thatincrementally-stretched adhesively-laminated films of one or moreimplementations can allow for a reduction in basis weight (gauge byweight) as much as 50% and still provide enhanced strength parameters.

In addition to allowing for films with less raw material yet enhancedstrength parameters, the results from Table VI further shows thatincrementally-stretched adhesively-laminated films of one or moreimplementations can have an increased gauge (i.e., caliper) despite thereduction in basis weight. Some consumers may associate thinner filmswith decreased strength. Indeed, such consumers may feel that they arereceiving less value for their money when purchasing thermoplastic filmproducts with smaller gauges. One will appreciate in light of thedisclosure herein that despite a reduction in raw material,incrementally-stretched adhesively-laminated films of one or moreimplementations may be and look thicker than a single layer of film witha higher basis weight. Thus, one or more implementations can enhance thelook and feel of a film in addition to enhancing the strength parametersof the film.

In an additional example, one white layer of HDPE with a low MD tearresistance was cold stretched by MD ring rolling at 0.110 DOE. Anotherblack layer of LLDPE was cold stretched by MD ring rolling at 0.110 DOEfollowed by TD ring rolling at 0.032 DOE and then laminated togetherwith the same adhesive. Again, with the two ply laminates superiorproperties were obtained even at very low adhesive levels compared to asingle ply film as shown by the results of Table VII.

TABLE VII Dynatup and Tear Resistance of Incrementally-StretchedAdhesively- Laminated Films (1 layer MD RR and 1 layer MD and TD RR)Coat Gage Dynatup Dynatup Dart Wt. by Peak Energy to Drop MD TD g/sq.Wt. Load max load F50 Tear Tear ft. (mils) (lb-f) (in. lb-f) (g) (g) (g)Sample 10 0.0300 0.67 11.83 11.86 284 357 575 Sample 11 0.0150 0.6711.79 14.21 357 532 Sample 12 0.0100 0.67 10.99 10.77 288 373 502 Sample13 0.0075 0.67 11.80 11.60 360 530 Sample 14 0.0060 0.67 12.60 10.57 260385 535 Comparison Data Thicker NA 0.9 4.3 3.8 180 262 843 Base Film

In a final example, a bag formed from an incrementally-stretchedadhesively-laminated film were compared to single ply bags of heavierbasis weight using a consumer test with 17 lbs. of mixed garbage on anend use scale of 1-5. The laminate of two layers which wereindependently MD ring rolled and then TD ring rolled followed byadhesive lamination has an excellent score comparable to single layerbags of higher basis weight.

TABLE VIII End Use Testing Sample Gage by Wt. (mils) End use scoreIncrementally-Stretched 0.66 4.16 Adhesively-Laminated MD ring rolledsingle layer 0.80 4.08 Strainable network single layer 0.85 4.50

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. Thus, thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes that come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

We claim:
 1. A thermoplastic bag with a bag-in-bag configuration,comprising: a first thermoplastic bag having at least a bottom section,a middle section, and an upper section, the first thermoplastic bagcomprising first and second opposing sidewalls joined together alongthree edges; a second thermoplastic bag positioned within the firstthermoplastic bag, the second thermoplastic bag having at least a bottomsection, a middle section, and an upper section, the secondthermoplastic bag comprising third and fourth opposing sidewalls joinedtogether along three edges; and a first plurality of non-continuousbonded regions securing at least one of the respective bottom sections,middle sections, or upper sections of the first thermoplastic bag andthe second thermoplastic bag together.
 2. The thermoplastic bag asrecited in claim 1, further comprising a second plurality ofnon-continuous bonded regions securing at least another of therespective bottom sections, middle sections, and upper sections of thefirst thermoplastic bag and the second thermoplastic bag together,wherein the second plurality of non-continuous bonded regions differsfrom the first plurality of non-continuous bonded regions.
 3. Thethermoplastic bag as recited in claim 2, wherein: the first plurality ofnon-continuous bonded regions comprise a first pattern; and the secondplurality of non-continuous bonded regions comprise a second patterndiffering from the first pattern.
 4. The thermoplastic bag as recited inclaim 2, wherein: the first plurality of non-continuous bonded regionscomprise one of ultrasonic bonds, adhesive bonds, bonds formed from MDring rolling, bonds formed from TD ring rolling, bonds formed fromembossing, or bonds formed from SELFing; and the second plurality ofnon-continuous bonded regions comprise another of ultrasonic bonds,adhesive bonds, bonds formed from MD ring rolling, bonds formed from TDring rolling, bonds formed from embossing, or bonds formed from SELFing.5. The thermoplastic bag as recited in claim 4, wherein the respectivebottom sections of the first thermoplastic bag and the secondthermoplastic bag are non-continuously bonded together by a plurality ofbonds formed from SELFing.
 6. The thermoplastic bag as recited in claim5, wherein the respective middle sections of the first thermoplastic bagand the second thermoplastic bag are non-continuously bonded together bya plurality of bonds formed from TD ring rolling.
 7. The thermoplasticbag as recited in claim 1, wherein another of the respective bottomsections, middle sections, and upper sections of the first thermoplasticbag and the second thermoplastic bag are un-laminated.
 8. Thethermoplastic bag as recited in claim 1, further comprising a thirdplurality of non-continuous bonded regions securing another of therespective bottom sections, middle sections, or upper sections of thefirst thermoplastic bag and the second thermoplastic bag together. 9.The thermoplastic bag as recited in claim 8, wherein the third pluralityof non-continuous bonded regions differs from both the first and secondpluralities of non-continuous bonded regions.
 10. The thermoplastic bagas recited in claim 1, wherein one or more of the first thermoplasticbag or the second thermoplastic bag is incrementally cold stretched. 11.The thermoplastic bag as recited in claim 10, wherein one or more of thefirst thermoplastic bag or the second thermoplastic bag is MD ringrolled.
 12. A multi-layered bag, comprising: a first sidewall comprisinga first layer of a thermoplastic material and an adjacent second layerof thermoplastic material; a second sidewall comprising a first layer ofa thermoplastic material and an adjacent second layer of thermoplasticmaterial, wherein: the second sidewall is joined to the first sidewallalong a first side edge, an opposing second side edge, and a bottomedge, and at least a portion of respective top edges of the first andsecond sidewalls define an opening of the multi-layered bag; and a firstplurality of non-continuous bonds securing at least one section of thefirst and second layers of the first sidewall together.
 13. Themulti-layered bag as recited in claim 12, a second plurality ofnon-continuous bonds securing at least another section of the first andsecond layers of the first sidewall together, the second plurality ofnon-continuous bonds differing from the first plurality ofnon-continuous bonds.
 14. The multi-layered bag as recited in claim 12,wherein: the first plurality of non-continuous bonds are discontinuous;and the second plurality of non-continuous bonds are partiallydiscontinuous.
 15. The multi-layered bag as recited in claim 12,wherein: the first plurality of non-continuous bonds comprise one ofultrasonic bonds, adhesive bonds, bonds formed from MD ring rolling,bonds formed from TD ring rolling, bonds formed from embossing, or bondsformed from SELFing; and the second plurality of non-continuous bondscomprise another of ultrasonic bonds, adhesive bonds, bonds formed fromMD ring rolling, bonds formed from TD ring rolling, bonds formed fromembossing, or bonds formed from SELFing.
 16. The multi-layered bag asrecited in claim 12, wherein one or more of the first and second layersof the first sidewall and the second sidewall are incrementallystretched.
 17. The multi-layered bag as recited in claim 12, wherein:the at least one section is adjacent the opening; and the at leastanother section is adjacent the bottom edge.
 18. The multi-layered bagas recited in claim 12, wherein: the at least one section comprises amiddle section of the first sidewall; and the at least another sectionis adjacent the bottom edge.
 19. A method for forming a discretelylaminated, multi-layered thermoplastic bag, the method comprising:providing first and second thermoplastic films; non-continuouslylaminating a portion of a first thermoplastic film to a secondthermoplastic film by a first process selected from the group consistingof adhesive bonding, ultrasonic bonding, embossing, ring rolling,SELFing, and combinations thereof; and joining at least two edges of thefirst thermoplastic film and the second thermoplastic film together toform a bag configuration.
 20. The method as recited in claim 19, furthercomprising: non-continuously laminating a second portion of the firstthermoplastic film to the second thermoplastic film by a second processselected from the group consisting of adhesive bonding, ultrasonicbonding, embossing, ring rolling, SELFing, and combinations thereof;wherein the first process differs from the second process.
 21. Themethod as recited in claim 20, further comprising cold incrementallystretching one or more of the first thermoplastic film and the secondthermoplastic film prior to non-continuously laminating the firstthermoplastic film to the second thermoplastic film.